Steering brake



March'5, 1946. H. A. KNOX STEERING BRAKE Filed Jan. 29, 1944 s Sfieets-Sheet 1 x D n A U, P

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' KNOX STEERING BRAKE Filed Jan. 29 1944 s Sheets-Sheet 2 v h x 5 C l I... 9 .m' M 5 f." .1 i.

March 5,1946, H, A, KNOX 2,395,882

STEERING BRAKE Filed Jan. 29, 1944 $Sheets-Sheet 3' Hum A. KI'LCIX with anchorage, so constructed Patented Mar. 5, 1946 STEERING BRAKE 7 Harry A. Knox, Washington, D. C- Application January 29, 1944, Serial no; 520,1 8 8 Claims. (01. 188-77) (Granted under the act amended April-30, 1928; 370 O. G. 757) The invention described herein may be man factured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

The invention relates to brakes, and while in many respects applicable to general use, is specifically valuable for use in steering brakes for rugged transmissions commonly used in endless track tractive engines, such as Bull-dozersjf tractors, and military machines such as armored tanks, wherein steering is effected by selective braking or locking of one or the other of two traction elements between which a difierential driving gear is connected. This type of steering has been common over a long period, and in most military uses involves severe load stresses and shock to the braking means. With the advent of tanks the brakes used operated well enough in those machines during the war of 1914-18. The great increase in armor, and armament, with accom-v panying greater size and heavier framing, increase in size of crews and auxiliary equipment and the recent requirements for high speeds accompanied by the installation of high pOWer motors including airplane type radial motors, has shown the conventional brake totally inadequate. Limitation of space has made enlargement of common drums impracticable and excessive weight has also been a material factor making the solution of the brake difiicult.

It is therefore a paramount object of the invention to provide a brake adapted to oppose momentum inertia of the'greatly augmented masses of tanks and their loads together with the aug merited forces transmitted from the power plants of these machines, w le at the same time avoiding the making of demands for increasedspace for the brake and also enabling its operation by the pedals and linkage heretofore used to operate.

smaller or less eifective brakes, aswell as avoid.- ing requirement for greater extent of movement of pedals or the brake levers and linkages between the pedals and brake shoes.

In this direction it is an aim to give a multiple rooved drum brake with a novel form of shoe structure therefor, having characteristics contributing to increased effectiveness as well as afiording greatly increased braking surface within a given axial dimension and diameter of drum.

A further animating motive is to present a new and effective linkage and force-amplifying means and organized that the added torque stresses are amply opposed problem of an adequate steering of March a, 1883, as

and accommodated in a relatively reducedspaoe and with a greatly simplified'structure; 1

Another attainment of value is the encasement of the brake unit within a minimum, spaceand weight of material, and embodying a. nV e1 C0Ol dination of case and operative, parts.

' power plant.

'It is'a further. valuable featurethat the parts required are producible, with an" absence of'com plieations in production and assembly; enabling the use of conventional practices in manufacture, and conventional forms of elements inlarge part.

Additionatobjects; advantages and featuresof invention liein the construction arrangement and combination of parts, involved in theembodiment of the invention, as will become apparent .from

the following description and drawings,- whereinz Figure. 1, is alvertical sectional view of one embodiment of thejinv'ention;

Figure 2 is an elevational in a'plane with the line 2-2"of'F igure 1; j 1

operating yokesi' 7 V 1 Figure 4 is .a section on the line 4'.4'ofFigurel; Figure?) is a section on the line 55 of Figure 1. Referring to the drawings, there is illustrated a Figure 3 is a detail perspective ofjoneof the casestructure ill, in whichiithere is journalled :a

shaft. I I, which may be one .oftwofcoaxial counter shafts connectedbythe usuali differential gearing (not shown) dividing the; force receivedjfrom a A sleevegear IZsuitable for transmitting power to a tractive unit at one side ofa vehicle is shown splined on the shaft, antifrietion bearings l3 and I4 supporting the gear being mounted ina recessed partofthe adjacent end an.'inward annular extension lfi from the wall, respectively; The fextensiong'lfi afiords a substantially cylindrical chamber inte riorly relieved between the .bearingsand stilfened exteriorlyby a number ofjwebs l1. 1 I Immediately adjacent and inwardlyof theextension l6 a drum hub I8 is splined on a sleeve l8, revoluble on the-shaft and operatively. connected to the shaft by differential means not, shown; The hub is .rabbetedatits fouterend to accommo-- date antifrictionbearing. l9 supporting. thehub and based on the inner end of the gear sleeve 12 which stops at the inner side of the rabbetgf 'f' V The, hub is formed with a eircumscribln g cylindrical drum seat 20 at its outer ,end,;integ;ral with which, and spflcedjfrompne extremity of the seat, there'is, anumber of peripheral spaced View. approximately 2 lugs 2|.

Bolts 24 are engaged, though the lugs and flange, held with locked nuts, by which the flange is drawn tightly on to the seat and against the lugs. The drum has a broad rim formed with a multiplicity of circumscribing V.-grooves 25 (five being shown) of uniform depth and closely spaced axially n the drum, the sides of each groove being disposed at an angle. of approximately forty degrees to each other, measured in a radial plane. The width of the groove is thus approximately of the altitude of the vertex of the bottoms of the grooves, however, are notformed by an angular junction of the sides, but are rounded a, distance short ofthe geometrically projected vertex of opposite elements of the groove sides. The case It) includes a top plate portion 21 somewhat below the top of the drum, and on this there is formed an oblique forwardly inclined eupola extension 28 over and around the drum, having an opening 29, bounded by .an inclined rear wall 39, and inner and outer vertical side walls 3| and 32 formed integrally with the flat top plate. The forward edge of the opening is at the level of the top late and this and the other edges of the opening 29 formed by the walls named are finished in a plane inclined upwardly from front to rear. A cover plate 33 is bolted over the opening 29 on which there is a central raised operator and adjuster housing 34. The side walls of the housing 34 are formed with hushed bearings 35 in 'which'there is ievolubly mounted a brakeoperating rock shaft 36, enlarged within the housing, one end of the shaft stopping within the wall of the housing where the opening is closed outwardly of the shaft by a plug disc 39', the opposite end of the shaft being extended through the side of the housing and an operating lever 31 fixed thereon. Near respective ends the enlarged part of the shaft in the housing has two cylindricalparallel diametrical openings 38' therethrough normal to the shaft axis. T-wo studs 39 on a toggle yoke 49 are slidably inserted through these openings from one side, these studs having a length substantially greater than thediameter of the shaft. The yoke 49 consists of a broad, bored bearing eye 4|, with its axis parallel to the shaft, from one side of which there areextended divergent arms 42 substantially in a radial plane from theeye, and at a distance from the eye 4| the arms are extended asstud bases 43 in a plane oblique to that in which the arms are laid, and, in a plane parallel to and spaced from the shaft and the eye 4|, the bases being also spaced apart more than the width of. the eye. Set in the bases there are respective studs 39 which are thus in a common plane at an acute angle to theplane of the arms 42, so that the axis of the eye is spaced only a short distance from theplane of the studs and is near the shaft 39. From each of the bases 43 parallel short arms 44 are extended obliquely from the laneof the bases 43, toward the same side On which the studs extend, and beside the shaft. At their extremities coaxial trunnions 45 are set, projecting toward but stopping short of each other and on an axis parallel to that of the eye 4| and slightly nearer the plane of the studs. With the studs 39 insorted in the the axes of the eye 4| and the trunnions 45..

The eye 4|, located at therear of the. shaft, has a'heavy pin 45 engaged therethrough, and

projecting at each side, on which there are hung angle subtended; The

- nected thereto by cross shaft, the latter thus lies between four anchor links 41, through the extremities of which a similar cross pin 49 is engaged, and to which pin there are also connected the extremities of five curved brake segments or shoes 50, laid in respective grooves 25 of the drum, and each having at each end pairs of transverely spaced radially extended ears 49 through one set of which the pin 48 is engaged. There is a chain series of the shoes laid around the drum in each groove, each two mutually adjacent shoes .being connected by a short coupling link 5| laid between the ears 49 and conpins 48. Each segment or shoe 59 has an inner portion conforming to the shape of 'the groove in cross section and stopping short of the bottom of the groove. They are made of material appropriate to brake use, heretofore known or which may become available, such as cast iron and bronze.

Between the two links 41 at each end of the cross pin 49, an anchor 52 is mounted on the cover housing, consisting of a stud piece set against a shoulder 53 on the inside of the housing over the links 41, the stud extending obliquely inward and downward toward the drum in a counter clockwise direction, and having a saddle earing recess-54 across the end, into which the pin 46 is set. The anchor is provided with a bolt stud 55 in its base extended longitudinally therefrom and outward through the housing and secured by an exterior nut 56 which draws the anchor tightly against the shoulder 53. A plane normal to the shoulder 53 and through the middle of the saddle recess 54 is tangent to the arc of movement of the pin 46 with the shaft 33 and away from the seats 54 (should such movement'occur), when the parts areassembled as shown in Figure 1, so that the pin '46 is free for movement away from engagement in the saddle recess in case of need, as will appear.

The opposite or forward end of the brake chain terminates close to a tangent of the drum passing closely inward of the trunnions 45, so that a line through the axes of the trunnions and of the last cross pin 48 in the brake segments is parallel to such tangent at a medial position (in their range of operative movement) of the principal operating parts connected to this end of the shoe chain. Connected to the last cross pin at the forward end of the brake chain there is a connector El, which is a fork head having five ears 53 alined with respective terminal brake segments and secured between the respective pairs of ears thereof by the pin 48. The connector has an interiorly threaded tubular shank v59, of substantial length, into which there is screwed an adjusting rod and link 99 which is extended upwardly and rearwardly at a slight inclination, between the inner ends of the trunnions 45 and through the top, of the housing 34 and a distance beyond. Its upper end is formed with a hexagon head iii.- The top wall of the housing is formed with a rabbetted opening 52 clearing the stem liberally and a dust excluding washer 93 is confined in the rabbet, closely fitted to the rod and retained by a cover washer 64. a y

A collar 95 is pinned on the rod close below the trunnions 53 to receive downward thrust of the trunnions, and on the rod over the trunnions there is a guide block 69 adapted to receive on its lower end the upward thrust of the trunnions. The rod is revoluble in the block and is formed with an integral enlarged collar or shoulder 51 resting on the upper side of the block; and located a distance below the top of the housing.

' asaasaa The block is supported for upward sliding'and tilting movement with the rod by means of heavy pivot and guide pins 68 set in transversely boredbosses 69, on the housing, and also engaged In operation, when the parts are assembled as described, the released'position is as shown in full line in chain closer of the lever 3'! involves a reverse sequence in functions, counterclockwise movement of the shaft 36 forcing the brake shoes to release the drum.

In the brake applying operation, the rod 60 and block 66 IOI At this position the rod i the pivots.

of the shaft 36'carrying the yoke 4:], draws the pin 46 fromthe seats in the'a'nchor studs 52, the

their inistuds 39 tending to draw slightly from tial position in the shaft 36. A i

The brak'thlls has a double anchor function and structure so that torque or winding in components of the forces a plied and the resistance stresses in the brake parts.

It should also be noted that as the shoe segments wear the axes of the cross pins 46 and 48 move inward toward the drum. This involves a slight compensating pivotal inward swing of the its lower end the pins 68 serving as The block 66 has a slight similar wardly to its seats in the anchors same time pushes the links 41 and rearward to released positions.

This brake differential drive system in tanks wherein when brake drum is locked against rotation the rate of rotation of the shaft II is reduced but not 52, and at the adjacent shoes tionally efiective. It may, however, be used also in other types of transmissions as will be apparent.

The links and shoes are slidable on the pins 46 d 48 so that good alinement of the direction sides of a shoe due to faults in material, or axial displacement of the drum.

I have disclosed the invention with particularity in the best form in which it has been developed at this time, but it will nevertheless be understood has formed a part of a controlled the drum mounted 4- that changes in the construction; arrangement, and combination of parts, substitution of materials and equivalents mechanical or otherwise may be made without departing from the spirit of the invention w'thin'the scope of the appended claims, wherein I claim:

.1. In a brake, .a drum, a rock shaft close to on an axis parallel to that of the drum, means to rock the shaft, a flexible brake device extended around the drum, a yoke device having a diametrically slidable connection with the shaft, and having opposite arms ex-. tended beside the shaft and connected to respec: tive ends of said brake device, and a fixed anchorage for one of said connections.

' .2. In a brake of the character descr'bed a brake I operating member of limited movement, a direct brake connection member, a mounting, a guide device pivoted thereon on an axis transverse to the direction of movement of said operating mem her, an adjusting member slidab le and revoluble therein on an axis coincident with said direc tion and having screw engagement with said con.- nection member, means to limit sliding movement of said adjusting member in one direction, said operating member having a revoluble non-sliding connection with said adjusting member.

3. In a brake of the character described a brake connecting member, a mounting, a guide pivoted thereon'and slidable away from. and toward said connecting member, an adjusting rod engaged revolubly through said guide and having screw engagement with said connecting member means to limit sliding movement of the adjusting rod in the direction of said connection and a brake operating member revolubly engaged with the rod.

4. The brake structure of claim 3 in which said mounting comprises opposed pivot pins adjacent opposite sides of said rod, said guide having Ion.- gitudinal slots receiving said pins and constitute ing part of said means to limit sliding movement of the adjusting rod.

5. The structure of claim 3 in which said mounting comprises opposed pivot pins in close 45 access:

radial relation to said rod said guide having longitudinal slots receiving the pins at least one of said pins having a spring loaded rounded wiper thereon. said-rod having a plurality of longitudinail grooves adjacent said wiper and extending a dis ance equal to the range of movement of said rod there adjacent. Y

6, Thestructurc of claim 1 in which said anchorage consists of a saddle bearing having its open side presented in a direction opposite normal rotation ofthe drum and in the direction of application movement of the adjacent said connection betweenthe yoke and brake device.

7. In a brake, a revoluble brake drum, a shaft revoluble onan axis parallel to that of the drum, a flexible shoe device around the r & fi anchorage engaged with one end thereof adjacent the shaft, angularly spaced eccentric connections between the shaft and respective ends of said shoe device, and means to rock the shaft, said anchcra e being an abutment device, said brake device having a part at one end constructed and arranged to engage the abutment under rotation with the drum in one direction said eccentric connections comprising a rigid member radially movable on said s aft and having respective ends of the brake device connected thereto for application of draft forces in respective directions, under rotation of the shaft.

8. In a brake of the character described, a multiple grooved drum, a flexible shoe device in respective grooves thereof each consisting of a plurality of separate rigid groove-fitting segments connected in chain relation in each groove and draft connections at each end of the shoe, said connections between segments and at least one draft connection each including a transverse pivot pin, said segments being engaged for lateral slidable movement on the pin in variable mutually spaced relation whereby automatic lateral adjustment of the segments on said pin will occur under unbalanced pressure of the segments against the sides of the grooves.

HARRY A. KNOX. 

